What\'s the difference between 80\'s manual and automatic driveshafts? The reason I'm asking is that in the LMC blazer catalog, they only sell one front driveshaft for 81-91 blazers, whereas they sell separate manual and auto driveshafts for 80' and earlier. They don't sell rear driveshafts, at least not anymore. The reason I'm asking is I'll be doing the classic 700R4 to SM465 swap this summer and it would be great if I could use my original driveshafts. If they are different, is it the lengths of the shafts? the U-joints?